I used the River Cottage recipe which is very adaptable...
1kg marrows/overgrown courgettes, unpeeled but cut into dice no bigger than 1cm (discard seeds from really large marrows) OR 1kg pumpkin, peeled, seeds and soft fibres discarded, and diced no bigger than 1cm
1kg red or green tomatoes, scalded, skinned and roughly chopped OR 1kg plums, stoned and chopped
1kg cooking or eating apples, peeled and diced
500g onions, peeled and diced
500g sultanas or raisins
500g light brown sugar
750ml white wine or cider vinegar, made up to 1 litre with water
1–3 tsp dried chilli flakes
1 tsp salt
for the spice bag
1 thumb-sized nugget of fresh or dried ginger, roughly chopped
12 black peppercorns
1 generous tsp coriander seeds
a few blades of mace
..and in my case I used ripe tomatoes and a mix of red wine vinegar and malt vinegar, as that was all I had and the local store did not have any cider vinegar which I prefer. It took me a few hours, but now I've got 6 and a bit large jars in the cupboard. I really don't like to be without my own Marmalade, Chutney...or jam come to think of it.